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Tyrant

OP Performance

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Tyrant    0

Hiya, has anyone got any statistics for what kind of performance the OP can be expected to give, in terms of how many objects per frame?

 

Right now I've got it displaying one big background (640x480 interlaced) image, with 64 sprites (16x16 4-bit transparent bitmaps) over the top, and it's behaving strangely.

 

In some arrangements of the images, it displays them just fine... but if I change their locations / arrangement, all I get is a black screen.

 

From my experiments, it seems it will display all 64 on one line with no problem, 32x2 also no problem, 16x4 sometimes but not always, and never an 8x8 grid of them. My list isn't broken into sections by height (yet, I'm considering it but I'm not sure the best way to do it), so the sprite objects are just laid out left to right, top to bottom. I thought at first it was an issue with the number of objects per line, but since I can fit all 64 on one line, but cannot fit 8 on each of 8 lines, that doesn't make sense. I'm completely at a loss to explain it.

 

Also, when I re-arrange them into a grid of 4x16 (top to bottom, left to right) it displays fine, but if I try 4x16 (left to right, top to bottom) or 16x4 (top to bottom, left to right) it gives me a black screen.

 

Does anyone have any idea what's going on here, or in a more general sense, what kind of performance I can expect to get from the OP?

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SCPCD    0

Hi !

 

The OP is only limited by the bandwidth to draw a line :

the OP need to go from the first object to the stop object in less than 64us (for PAL) and 63.5us (for NTSC) to draw a line.

 

there is some timing diagram for 16-bit bitmap here : http://www.jagware.org/index.php?showtopic=465

and an introduction about OP utilisation on F.Act.S demo : http://www.jagware.org/index.php?s=&sh...post&p=9308

 

 

Your problem seems to be like a misalignement somewhere or an error on the compute of the OP list.

Have you dump your OP list from the jag when there is a black screen to see if there isn't an error ?

 

Does your program work on PT0.5 ? on "F9" you can see the Object List

Or on VirtualJaguar you can see OP list in the vj.log.

 

 

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Tyrant    0
Your problem seems to be like a misalignement somewhere or an error on the compute of the OP list.

With a clear head and a bit of "change the background colour to see how long it takes" timing of things shows me (I think) that the error is simply that it's not making it all the way through list creation by the time the OP starts to chew through the list. Hopefully double-buffering the list should make that problem go away, and I can get on with seeing quite how much I can put on screen at once.

 

Thanks for your help.

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Matmook    1
Does your program work on PT0.5 ? on "F9" you can see the Object List

I've just tried that and it's a very interesting feature ! ;)

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